Evaluation of ultrasonic cavitation effect on toxicogenic algae

Summary

In the «Russian Federation National System of Chemical and Biological Safety (2009–2014)» Federal Task Program it is noticed that in Russia lots and lots of pollutants are discharged annually into surface waters. As a result deleterious hydrobionts, blue-green algae Cyanophyta (cyanobacteria) in particular, started dominating in fresh water bodies. In the process of lysis of these prokaryotes cancerogenic microcystines and neurotropic saxitoxins are formed; whereas in the process of chlorination in water treatment significant amounts of toxic halomethanes are formed. Research workers of Limnology Institute of the Russian Academy of Sciences (St. Petersburg) are studying in detail the potential of using ultrasonic cavitation and ultrasonic irradiation in combination with coagulation/flocculation in water treatment. In the experimental studies water samples with algae: unicellular and multicellular green algae, Xantophyta, diatomite algae and blue-green algae were used. The algae were either cultivated in the laboratory or the relative samples were taken from the ponds and lakes of St. Petersburg. The toxicity of the water samples before and after ultrasonic treatment of algae was determined by the method of biotesting and biorecognition with the use of cladocerans Daphnia magna. The concentration of chlorophyll was determined according to 17.1.4.02-90 State Standard (GOST). It was found that under the effect of ultrasonic cavitation the destruction of blue-green algae and water detoxification occurred. The obtained results of evaluating the effect of ultrasonic cavitation on toxinogenic algae instill confidence in the viability of the given processing technology. Needless to say that the development of the relative ultrasonic devices of acceptable power consumption provides for extending the scope of using the method for weedy water treatment.

Key words

natural water , eutrophication , blue-green algae , cyanotoxins , microcystines , saxitoxins , ultrasonic cavitation